Hey Y'all,

I'm going to be swapping out my well worn LB9 for a Corvette L98. It comes with the the Corvette exhaust manifolds attached. Looking at the design, it clearly won't mate up with the factory Y pipe. So I've got 3 options;

1) use the existing manifold setup for the LB9 (easiest and a no cost option)
2) have the Y pipe modified to meet up with the exhaust manifold from the Corvette L98
3) get some shorty headers and Y pipe (what drops in without a fuss?)

What do you all recommend?

 

I'm pretty sure the L98 heads are d port heads. I had them on my zz4. Those heads won't work w regular rectangle port manifolds. I used headers that worked w them. Initially I used Edelbrock headers and now dons headers w my fastburn heads, also D port. So I think you need to use the vette manifolds w a custom y pipe or a set of headers. IDK if vette manifolds will fit our frame or not. If I were you I'd try and get a set of dons headers while he's still making them.

I'll admit I'm not the most informed on L98 vette stuff but I'd look at the differences in exhaust ports.

 

The Y body manifolds dump in the center. I can't imagine them fitting.

 

Corvette stuff doesn't fit.

 

The stock exhaust that came on these cars was horrible. My vote is always for headers and a properly sized system.

 

Gets my vote as well. The manifolds were the worst flowing ever created for a SBC.

 

Two best mods I made on my 88 was the rear gearing and headers/exhaust. Really woke up the car!

 

The LB9 manifolds from your 85' should bolt up and work. These are the same manifolds GM used in the 350HO conversion kit they offered in the 90's for thirdgen F-bodies. That kit included a ZZ4 crate, which had the same Corvette L98 aluminum heads. So, yes it will bolt up and work.

No idea if the manifold ports will partially block the D-ports of the heads and perhaps some die grinder work would fix that. The manifolds were certainly be more restrictive than headers, but headers come with their own issues.

As other have stated, the Corvette manifolds are not going to work.

 

I have an exhaust somewhere in my LB9 system. When I stand by the car on the passenger side, I can feel pulses of air from under the car. I went ahead and bought some Doug's shorty headers and Y pipe. Hopefully, that nips all my concerns in one solution.

 

Solves some problems and creates new ones. I do like headers, but they are more hassle than manifolds.